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# Distillation Design MCQ’s – Key Components of Multicomponent Distillation

For the light key component, Equilibrium relation is

a) yK=x

b) Kx=y

c) Depend upon trays

d) Can’t be specified

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Answer: a

Explanation: Here Kx=y is the equilibrium relation, which does not depends upon the number of trays or the vice versa relation i.e. Kx=y representing x and y moles of gas and fluid.

If the fractional recovery of light key in the distillate is F_{R}, then light key in the feed is

a) Dx_{D}= (FR_{D})+Fx_{LK}

b) Dx_{D}= (FR_{D})/Fx_{LK}

c) Dx_{D}= (FR_{D})Fx_{LK}

d) Dx_{D}= (FR_{D})

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Answer: c

Explanation: The definition of the fractional recovery is Dx_{D}= (FR_{D}) Fx_{LK}, while gives us the material balance on feed and distillate Dx_{D}= (FR_{D}).

For multi-component systems, Underwood Equations gives

a) Minimum Reflux

b) Minimum Strip

c) Maximum Reflux

d) Minimum Trays

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Answer: a

Explanation: Underwood Equations gives Minimum Reflux, Fenske’s equation gives minimum Trays and McCabe gives us minimum Reflux.

Gilliland Correlation is arranged to estimate the

a) Numbers of Stages

b) Numbers of Reboiler

c) Numbers of Feed

d) Numbers of Column

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Answer: a

Explanation: Gilliland Correlation is arranged to estimate the Numbers of Stages at finite reflux ratio, while reboiler is only a unit piece of set.

Gilliland’s y intercept is given as

a) N_{min}/N+1

b) N-N_{min}/N+1

c) N+N_{min}/N+1

d) N/N+1

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Answer: b

Explanation: Gilliland represented correlation graphically as, N-N_{min}/N+1 on y axis, where N is the number of stages.

Gilliland’s x intercept is given as

a) R_{min}/R+1

b) R/R+1

c) N_{min}/R+1

d) R-R_{min}/R+1

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Answer: d

Explanation: Gilliland represented correlation graphically as R-R_{min}/R+1 on x axis, where R is the reflux ratio of the system.

Optimum feed-stage location, can be obtained by using

a) Gilliland correlation

b) Kirk bride correlation

c) Fenske’s correlation

d) Sorel’s correlation

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Answer: b

Explanation: An approximate optimum feed-stage location, can be obtained by Equation of Kirk bride correlation while Gilliland correlation is used to plot intercepts.

For Multicomponent Mixtures Equilibria depend on ?

a) Pressure

b) Temperature

c) Humidity

d) Enthalpy

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Answer: b

Explanation: It depends on T, which changes from stage to stage, Pressure is not the deciding criteria as it can vary from Colum to column.

In multicomponent distillation, the separation of components is calculated using

a) Assumed flows of species

b) Assumed flows of reflux

c) Assumed flows of Vapor

d) Assumed flows of liquid

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Answer: c

Explanation: The number of plates above and below the feed is assumed, and the separation is calculated using assumed reflux.

Once the components are identified, in a multicomponent distillation they are called

a) Key Components

b) Mixed Components

c) Flow Components

d) Gain Components

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Answer: a

Explanation: Once the components are identified, they are called Key Components, the components which are hence mixed in a single stage rate called mixed components.